Optical proximity sensors with reconfigurable photo diode array

ABSTRACT

Optical proximity sensors, methods for use therewith, and systems including optical proximity sensor are described herein. Such an optical proximity sensor includes a light source and a light detector, wherein the light detector includes a plurality of individually selectable photodiodes (PDs). During a calibration mode, individual PDs of the plurality of PDs of the light detector are tested to identify which PDs are crosstalk dominated. During an operation mode, the PDs of the light detector that were not identified as being crosstalk dominated are used to produce a light detection value or signal that is useful for detecting the presence, proximity and/or motion of an object within the sense region of the optical proximity sensor. By not using the PDs that were identified as being crosstalk dominated, the signal-to-noise ratio of the light detection value or signal is improved compared to if the crosstalk dominated PDs were also used.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 14/523,202 filed Oct. 24, 2014, now U.S. Pat. No. 9,772,398,which application claims priority to U.S. Provisional Patent ApplicationNo. 62/017,737 filed Jun. 26, 2014, the contents of all suchapplications being incorporated herein by reference in their entirety.

BACKGROUND

Optical proximity sensors, which can also be referred to as opticalproximity detectors, typically include a light source and an adjacentphotosensitive light detector. Such optical proximity sensors can beused to detect the presence of an object, estimate proximity of anobject and/or detect motion of an object, based on the magnitude oflight originating from the light source that is reflected from an objectand detected by the light detector. The value of these sensors hasbecome more important with the advent of battery-operated handhelddevices, such as mobile phones. For example, a fair amount of the energyfrom a mobile phone battery is used to drive the display, and there isvalue in turning off the display or backlight when the mobile phone orother device is brought to the user's ear (where it cannot be viewedanyway). Optical proximity sensors have been used for this, and manyother applications.

For other examples, there are many other applications in which thepresence of an object can be detected with an optical proximity sensorto advantage. These range from sensing when protective covers have beenopened on machinery, paper has been positioned correctly in a printer,or an operator's hands are at risk near an operating machine. An opticalproximity sensor can also be used as a simple touch or near-touchactivated switch, and could be implemented in applications likekeyboards or devices that have a plastic housing that is sealed butwhich allows the light from the source to pass through and be sensed bythe detector on the return.

Light from the source to the detector that is not transmitted toward thetarget object, but rather is transmitted directly from the source to thedetector, is an example of optical crosstalk that reduces the capabilityof the overall device to sense distance. Such light essentiallypropagates sideways within the package and is considered noise or “lightleakage”, and contains no information. To reduce and preferably preventlight leakage, and more generally optical crosstalk, an opaque lightbarrier is typically used to isolate the light source from the lightdetector. However, light barriers are often imperfect, resulting inlight leaking under, over and/or through the barrier.

Optical proximity sensors are often used with (e.g., placed behindand/or covered by) a cover plate that is glass, plastic, or some otherprotective light transmissive material. For example, the cover plate canbe the glass covering a screen of a mobile phone, portable music playeror personal data assistant (PDA), or the plastic covering a screen of alaptop, netbook or tablet computer. When such a cover plate is placedover an optical proximity sensor, the optical proximity sensor is oftensusceptible to specular reflections. Specular reflections similarlyreduce the capability of the overall device to sense proximity, sincespecular reflections are essentially noise that contain no information.

In view of the above, there has been a desire to minimize light beingtransmitted directly from a light source to a light detector, as well asto minimize specular reflections and/or other internally reflectedlight. More generally, there is a desire to minimize optical crosstalkand/or the adverse effects thereof. Conventional attempts to achievethese goals typically relate to modification of themechanical/structural design of optical proximity sensors.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a top view of an exemplary optical proximity sensor.

FIG. 1B shows a cross-section view of the optical proximity sensor shownin FIG. 1A, along the dashed line B-B in FIG. 1A.

FIG. 2A shows a top view of an exemplary optical proximity sensor,according to an embodiment of the present invention.

FIG. 2B shows a cross-section view of the optical proximity sensor shownin FIG. 2A, along the dashed line B-B in FIG. 2A.

FIG. 3 illustrates additional details of the light detector of theoptical proximity sensor of FIGS. 2A and 2B, according to an embodiment.

FIG. 4 is a high level flow diagram that is used to describe a methodaccording to an embodiment of the present invention.

FIGS. 5, 6 and 7 are high level flow diagrams that are used to describeadditional details of step 404 that were introduced in FIG. 4 accordingto various embodiments.

FIG. 8 is a high level block diagram of a system including an opticalproximity sensor according to an embodiment of the present invention.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings that form a part hereof, and in which is shown byway of illustration specific illustrative embodiments. It is to beunderstood that other embodiments may be utilized and that mechanicaland electrical changes may be made. The following detailed descriptionis, therefore, not to be taken in a limiting sense. In the descriptionthat follows, like numerals or reference designators will be used torefer to like parts or elements throughout. In addition, the first digitof a reference number identifies the drawing in which the referencenumber first appears.

FIG. 1A shows a top view of an exemplary optical proximity sensor 102,which can be used to detect the presence of an object, estimateproximity of an object and/or detect motion of an object within a senseregion of the optical proximity sensor 102. FIG. 1B shows across-section view of the optical proximity sensor 102 shown in FIG. 1A,along the dashed line B-B in FIG. 1A. The optical proximity sensor 102includes a light source 104 and a light detector 106, which areseparated by one another by an opaque barrier 108. The optical proximitysensor 102 can optionally also include a glass or plastic cover plate110. Alternatively, the optical proximity sensor 102 can be included ina device (e.g., a mobile phone or tablet computer) that includes a coverplate behind which the optical proximity sensor 102 is placed. Eitherway, the optical proximity sensor 102 can be covered by a cover plate110 which may cause the light source 104 to detect specular reflectionsof light emitted by the light source 104. Traditionally, the lightdetector 106 of an optical proximity sensor, such as the opticalproximity sensor 102, has been implemented as a single large photodiode,or an array or matrix of smaller photodiodes that are hardwired to oneanother to essentially function as a single large photodiode.

The light source 104 is selectively driven to emit light. If an object112 is within the sense region of the optical proximity sensor 102, atleast a portion of the light emitted by the light source 104 will bereflected off the object 112 and will be incident on the light detector106. The light detector 106 generates an analog signal (e.g., a current)that is indicative of the intensity and/or phase of the light incidenton the light detector 106, and thus, can be used to detect the presenceof the object, estimate proximity of the object and/or detect motion ofthe object within the sense region of the optical proximity sensor 102.Such light can be generally referred to as light of interest or a signalof interest, and is represented by the dotted line 114 in FIG. 1B (aswell as in FIG. 2B). The light that originates from the light source andis reflected by an object and is incident on and detected by the lightdetector can also be referred to as a return signal.

The light detector 106 can also detect light that is not of interest (atleast with regard to detecting the proximity, presence and/or motion ofthe object 112) that can be caused by specular reflections and/or otherinternal reflections and/or light leaking under, over and/or through thebarrier 108. Such light that is not of interest (at least with regard todetecting the proximity, presence and/or motion of the object 112),shall be generally referred to as optical crosstalk, but can also bereferred to as interference light. Optical crosstalk degrades the signalto noise ratio (SNR) of an optical proximity sensor, and can reducemanufacturing yield where a percentage of manufactured optical proximitysensors do not meet predefined SNR requirements and thus must bescrapped. Embodiments of the present invention, which are describedbelow, can be used to reduce adverse effects of optical crosstalk andincrease yield, as will be appreciated from the following discussion.More specifically, certain embodiments described herein take advantageof the fact that optical crosstalk may be geographically localized toonly a certain area (or only certain areas) of the light detector 106,as will be appreciated from the discussion below.

FIG. 2A shows a top view of an exemplary optical proximity sensor 202,according to an embodiment of the present invention, which can be usedto detect the presence of an object, estimate proximity of an objectand/or detect motion of an object within a sense region of the opticalproximity sensor. FIG. 2B shows a cross-section view of the opticalproximity sensor 202 shown in FIG. 2A, along the dashed line B-B in FIG.2A.

Referring to FIG. 2B, the optical proximity sensor 202 includes a lightsource 204 and a light detector 206, which are separated by one anotherby an opaque barrier 208. The optical proximity sensor 202 canoptionally also include a glass or plastic cover plate 210, or can beincluded in a device that includes a cover plate behind which theoptical proximity sensor 202 is placed. Either way, the opticalproximity sensor 202 can be covered by a cover plate 210 which may causethe light source 204 to detect specular reflections of light emitted bythe light source 204.

The light source 204 can include one or more light emitting element(e.g., one or more light emitting diode (LED) or laser diode, but notlimited thereto) that emits infrared (IR) light, or light of some otherwavelength. While infrared (IR) light sources are often employed inoptical proximity sensors, because the human eye cannot detect IR light,the light source can alternatively produce light of other wavelengths.

The light detector 206 includes a plurality of individually selectablephotodiodes (PDs) 216. More specifically, in accordance with anembodiment, the light detector 206 includes an array or matrix of PDs216 that are not hardwired to one another, and thus, can be individuallyselected.

The light source 204 is selectively driven to emit light. If an object212 is within the sense region of the optical proximity sensor 202, atleast a portion of the light emitted by the light source 204 will bereflected off the object 212 and will be incident on the PDs 216 of thelight detector 206. Each of the PDs 216 of the light detector 206generates an analog signal (e.g., a current) that is indicative of theintensity and/or phase of the light incident on the PD 216, and thus,can be used to detect the presence of the object 212, estimate proximityof the object 212 and/or detect motion of the object 212 within thesense region of the optical proximity sensor 202. Such light can begenerally referred to as light of interest or a signal of interest, andis represented by the dotted line 214 in FIG. 2B.

The PDs 216 of the light detector 206 can also detect light that is notof interest (at least with regard to detecting the proximity, presenceand/or motion of the object 212) that can be caused by specularreflections and/or other internal reflections and/or light leakingunder, over and/or through the barrier 208. Such light that is not ofinterest (at least with regard to detecting the proximity, presenceand/or motion of the object 212), shall be generally referred to asoptical crosstalk, but can also be referred to as interference light.The embodiment of FIGS. 2A and 2B can be used to reduce detected opticalcrosstalk and increase yield, as will now be described.

Each of the PDs 216 of the light detector 206 would optimally produce nocurrent when there is no object (e.g., 212) within a sense region of theoptical proximity sensor 202 (the sense region may dependent on thefield of view and range of the optical proximity sensor). However, eachof the PDs 216 will likely produce some nominal dark current, which canbe referred to as a dark current component. Additionally, at least someof the PDs 216 (i.e., one or more) will likely also generate current (inaddition to the dark current) that is due to optical crosstalk, whichcan be referred to as a crosstalk current component.

In accordance with certain embodiments, those individual PDs 216 thatproduce an optical crosstalk component beyond a specified threshold areidentified as crosstalk dominated PDs. In accordance with certainembodiments, the responses to the crosstalk dominated PDs are thereafterignored, or the crosstalk dominated PDs are deactivated such that theydon't produce a response, or such that they don't contribute to theoverall signal produce by the light detector 206 or to the output of theoptical proximity sensor 202. More generally, cross talk dominated PDsare not used, during an operational mode, to produce a value or signalthat is useful for detecting the proximity, presence and/or motion of anobject.

In accordance with an embodiment, a calibration procedure can beperformed when there is no object within the sense region of the opticalproximity sensor 202 to identify which PDs 216, if any, are crosstalkdominated PDs. Alternatively, the calibration procedure can be performedwhile the plurality of PDs 216 of the light detector 206 are covered byan opaque material. Either way, during the calibration procedure none ofthe light that is emitted by the light source 204 and exits the opticalproximity sensor 202 should be detected by any of the PDs 216 of thelight detector 206. This way, during the calibration procedure any lightdetected by the PDs 216 of the light detector 206 can be presumed to bedue to optical crosstalk. The optical proximity sensor 202 can be saidto be in a calibration mode during the calibration procedure. Bycontrast, when the optical proximity sensor 202 is being used to producea light detection value or signal that is useful for detecting theproximity, presence and/or motion of the object, the optical proximitysensor 202 can be said to be in an operational mode.

In accordance with an embodiment, during the calibration procedure onlyone of the PDs 216 of the light detector 206 is selected at a time(e.g., sequentially) while the light source 204 is emitting light and aseparate value indicative of the amount of light detected by theselected PD 216 is determined and stored in memory or registers (e.g.,in a table) for each of the PDs. For example, a digital value can beproduced, using an analog-to-digital converter (ADC), in dependence on alight detection signal (e.g., a current) produced by the selected PD216. Depending upon implementation, such a light detection signal can beconverted from a current to a voltage by a transimpedance amplifier(TIA) and/or amplified (e.g., by a programmable amplifier) before it isprovided to the ADC. Thereafter, the PD(s) 216 having a value beyond aspecified threshold can be determined to be unacceptably responsive tooptical crosstalk, i.e., can be identified as being crosstalk dominated.During an operational mode of the optical proximity sensor 202, theresponses to the crosstalk dominated PDs can be ignored, or thecrosstalk dominated PDs can be deactivated such that they don't producea response, or such that they don't contribute to the overall responseof the light detector 206 or to the output of the optical proximitysensor 202. More generally, during the operational mode the cross talkdominated PDs are not used to produce the light detection value orsignal that is useful for detecting the proximity, presence and/ormotion of an object. Rather, only the PDs that are not cross talkdominated are used to produce such a light detection value or signal. Incertain embodiments, the digital values produced during the calibrationprocedure are stored in a non-volatile type of memory so that the valuesare not lost when the system is powered-down.

The threshold (used to determine whether PDs are crosstalk dominated)can be predefined and fixed. Alternatively, the threshold can beprogrammable. In another embodiment, the threshold can be determined bythe optical proximity sensor 202. For example, one or more calibrationPDs can be covered by an opaque mask (e.g., a metal layer) such that nolight should ever be incident on calibration PDs. Such calibration PDswill nevertheless produce a dark current, based on which a value can bedetermined and stored. The threshold can be specified to be equal tothis value, equal to this value plus an offset, or equal to this valuemultiplied by a factor (e.g., 1.2), or the like.

The more PDs 216 that get deactivated or ignored, the less the totalcurrent produced by the light sensor 206. If the magnitude of the totalcurrent is used to detect proximity (i.e., distance between an object onthe optical proximity sensor), this could be a problem, since proximityshould not be effected by how many PDs are activated. To avoid thisproblem, the optical proximity sensor 202 can be designed such duringoperation of the optical proximity sensor 202 (in contrast tocalibration of the optical proximity sensor) a first predefined numberor percentage of PDs 216 are used or activated and a second predefinednumber or percentage of the PDs 216 are deactivated or ignored. Forexample, 90% of the PDs can be used or activated, and 10% can bedeactivated or ignored. For a more specifically example, during thecalibration procedure the 10% (or some other percent) of the PDs thatare most effected by optical crosstalk can be identified and disabled orignored during the operation mode. Alternatively, the gain of the totalcurrent produced by the used or activated PDs can be adjusted based onhow many PDs are deactivated, ignored or otherwise not used to producethe light detection value or signal that is useful for detecting theproximity, presence and/or motion of an object. For example, if 10% ofthe PDs 216 of the light detector 206 are deactivated or ignored, thenthe total current produced by the used or activated PDs 216 can beamplified by 10%.

FIG. 3 illustrates additional details of the light detector 206,according to an embodiment of the present invention. Referring to FIG.3, the light detector 206 is shown as including a matrix of PDs 216, andmore specifically, m columns×n rows of PDs 216 _(column,row). A rowdecoder 302 is used to select which row is selected by selectivelyturning on and off switching transistors associated with the PDs 216. Acolumn decoder 304 is used to select which column is selected. A decodercontroller 305, or some other controller, is used to control the rowdecoder 302 and the column decoder 304.

In accordance with an embodiment, each of the PDs 216 is selected, oneat a time, during the calibration mode while the light source 204 isemitting light and a value indicative of the amount of light detected bythe selected PD 216 is determined and stored in memory or registers 312(e.g., in a table). More specifically, a current produced by theselected PD 216 is provided, by the column decoder 304, to atransimpedance amplifier (TIA) 306 that converts the current to avoltage. This voltage is optionally amplified by an amplifier 308 beforeit is provided to an ADC 312, which converts the voltage to a digitalvalue that is stored in the memory or registers 312. The stored digitalvalues can be compared (e.g., by one or more comparators or a processor)to a threshold used to identify which PDs 216 are crosstalk dominated.Thereafter, during operation of the optical proximity sensor 202 (asopposed to during the calibration mode), the responses to the crosstalkdominated PDs are ignored, or the crosstalk dominated PDs aredeactivated such that they don't produce a response, or such that theydon't contribute to the overall response of the light detector 206 orthe output of the optical proximity sensor 202. More generally, duringthe operational mode the PDs that are crosstalk dominated are not usedto produce a light detection value or signal that is useful fordetecting the proximity, presence and/or motion of an object within thesense region of the light detector 206.

Each of the TIA 306, amplifier 308, ADC 312 and memory or registers 312can be part of the optical proximity sensor 202, or one or more of thesecomponents can be external to the optical proximity sensor 202.Similarly, the decoder controller 305 can be part of the opticalproximity sensor 202, or can be external to the optical proximity sensor202. The optical proximity sensor 202 can also include a driver (notshown) for selectively driving the light source 204, or such a drivercan be external to the optical proximity sensor 202. In accordance withan embodiment, the amplifier 308 can be controlled to adjust theamplitude of the signal provided to the ADC 310 to be substantiallyequal to a target amplitude in order to increase and preferably optimizethe dynamic range of the ADC 310.

FIG. 4 is a high level flow diagram of a method for use with an opticalproximity sensor, including a light source and a light detector, whereinthe light detector includes a plurality of individually selectablephotodiodes (PDs). An example of such an optical proximity sensor wasdescribed above with reference to FIGS. 2A, 2B and 3. Referring to FIG.4, step 402 involves, during a calibration mode, identifying whichindividual PDs of the plurality of PDs of the light detector arecrosstalk dominated. Details of step 402, according to an embodiment,are described below with reference to FIG. 5. Still referring to FIG. 4,step 404 involves, during an operational mode, using the PDs of thelight detector that were not identified as being crosstalk dominated(and not using the PDs of the light detector that were identified asbeing crosstalk dominated) to produce a light detection value or signalthat is useful for detecting the presence, proximity and/or motion of anobject within the sense region of the optical proximity sensor. Thesense region can be defined by a field of view (FOV) of the lightdetector and the range of the light detector, but is not limitedthereto. Details of step 404, according to various embodiments, aredescribed below with reference to FIGS. 6 and 7. Still referring to FIG.4, step 406 involves, during the operational mode, using the lightdetection value or signal (produced at step 404) to detect the presence,proximity and/or motion of an object within the sense region of theoptical proximity sensor.

The presence, proximity and/or motion of an object within the senseregion can be detected using amplitude, phase and or time-of-flight(TOF) techniques, but are not limited thereto. If there is an objectwithin the sense region (i.e., field of view and range) of the opticalproximity sensor, infrared light (or other wavelength light) emitted bythe light source will be reflected from the object, and a portion of thereflected infrared light will be incident on the light detector. Inresponse to detecting light, the light detector is used to produce alight detection value or signal that is indicative of the magnitude andthe phase of the detected light. The magnitude of the light detectionsignal can be dependent, e.g., on the distance between the object andthe optical proximity sensor and the color of the object. In general,all other things being equal, the closer the object, the greater themagnitude of the light detection value or signal. Further, all otherthings being equal, if an object has a white color, or another highlyreflective color, the magnitude of the light detection value or signalwill be greater than if the object has a black color, or another lowlyreflective color. By contrast, the phase of the light detection signalshould be primarily dependent on the distance between the object and theoptical proximity sensor, and should not depend on the color orreflectivity of the object.

While not shown in FIGS. 2B or 3, one or more optical filter can belocated in front of the light detector 206 to reflect and/or absorbwavelengths that are not of interest. For a more specific example, oneor more optical filters can be used to reject ambient visible light andpass infrared light. Alternative and/or additional techniques forrejecting and/or compensating for ambient visible light can be used, asare known in the art.

Step 408 involves, during the operational mode, selecting a response oraction in dependence on the presence, proximity and/or motion of anobject within the sense region of the optical proximity sensor asdetected at 406. This can include, e.g., selectively enabling ordisabling a subsystem. Examples of such subsystems are described belowwith reference to FIG. 5.

FIG. 5 is a high level flow diagram that provides additional details ofstep 402, introduced in FIG. 4, according to an embodiment. Each of thesteps shown in FIG. 5 are performed during the calibration mode.Referring to FIG. 5, step 502 involves driving the light source to emitlight. Step 504 involves selecting each of the PDs one at a time, whilethe light source is emitting light, to thereby determine and store avalue for each of the PDs that is indicative of the amount of lightdetected by the PD. Step 506 involves identifying, based on the storedvalues, which individual PDs of the plurality of PDs of the lightdetector are crosstalk dominated. Step 506 can be achieved, as explainedabove, by comparing the stored values to a threshold value, andidentifying as being crosstalk dominated each of the PDs whose storedvalue exceeds the threshold. The threshold can be a predetermined fixedvalue or a programmable value. Alternatively, as explained above, avalue that corresponds to a dark current produced by a PD of the lightdetector can be determined, and the threshold value can be determinedbased on the value that corresponds to the dark current. For example, asexplained above, the threshold can be specified to be equal to thisvalue, equal to this value plus an offset, or equal to this valuemultiplied by a factor (e.g., 1.2), but is not limited thereto.

The row decoder 302, the column decoder 304 and the decoder controller305 can be used to perform step 504. For example, while a row isselected, one column at a time can be selected to separately determineand store a value for each of the PDs in the row that is indicative ofthe amount of light detected by the PD. Thereafter, while a next row isselected, one column at a time can be selected to separately determineand store a value for each of the PDs in that row that is indicative ofthe amount of light detected by the PD. This can be repeated for each ofthe rows. For another example, while a column is selected, one row at atime can be selected to separately determine and store a value for eachof the PDs in the column that is indicative of the amount of lightdetected by the PD. Thereafter, while a next column is selected, one rowat a time can be selected to separately determine and store a value foreach of the PDs in that column that is indicative of the amount of lightdetected by the PD. This can be repeated for each of the columns.

FIG. 6 is a high level flow diagram that is used to describe additionaldetails of step 404, introduced in FIG. 4, according to an embodiment.Each of the steps described with reference to FIG. 6 are performedduring the operational mode of the optical proximity sensor. Referringto FIG. 6, step 602 involves driving the light source to emit light.Step 604 involves selecting each of the PDs of the light detector one ata time, while the light source is emitting light, to thereby determineand store a value for each of the PDs of the light detector that isindicative of the amount of light detected by the PD. Step 604 can beperformed, e.g., using the components shown in FIG. 3, but are notlimited thereto. Step 606 involves adding the values stored for each ofthe PDs that were not identified as being crosstalk dominated (withoutadding the values stored for each of the PDs that were identified asbeing crosstalk dominated) to thereby produce a light detection valuethat is useful for detecting the presence, proximity and/or motion of anobject within the sense region of optical proximity sensor. Since valuesstored at step 604 for PDs that were identified as being crosstalkdominated are not added at step 606 (to produce the light detectionvalue), it is not necessary to even store values for the crosstalkdominated PDs. In other words, in an embodiment, step 604 can involveselecting each of the PDs that were not identified as being crosstalkdominated one at a time, while the light source is emitting light, tothereby determine and store a value for each of the PDs that were notidentified as being crosstalk dominated, wherein the value is indicativeof the amount of light detected by the PD.

FIG. 7 is a high level flow diagram that is used to describe additionaldetails of step 404, introduced in FIG. 4, according to anotherembodiment. Each of the steps described with reference to FIG. 7 areperformed during the operational mode of the optical proximity sensor.Referring to FIG. 7, step 702 involves connecting together each of thePDs that were not identified as being crosstalk dominated. This way thePDs that are not crosstalk dominated essentially function as one largePD. The PDs that are crosstalk dominated are not connected to the PDsthat are not crosstalk dominated, and thus, do not contribute to theresponse of the one large PD. Step 704 involves driving the light sourceto emit light. Step 706 involves, while the light source is emittinglight, using the connected together PDs that were not identified asbeing crosstalk dominated (i.e., that are not crosstalk dominated) toproduce a light detection signal that is useful for detecting thepresence, proximity and/or motion of an object within the sense regionof optical proximity sensor, wherein the light detection signal isindicative of the amount of light detected by connected together PDs.

Optical proximity sensors of embodiments of the present invention can beused in various systems, including, but not limited to, cell-phones andhandheld-devices. Referring to the system 800 of FIG. 8, for example,the optical proximity sensor 202 can be used to control whether asubsystem 806 (e.g., a touch-screen, display, backlight, virtual scrollwheel, virtual keypad, navigation pad, a camera, another sensor, acentral processing unit (CPU), a mechanical actuator, etc.) is enabledor disabled. For example, the optical proximity detector can detect whenan object (e.g., 212), such as a person's finger, is approaching, andbased on the detection either enable (or disable) a subsystem 806. Morespecifically, an output of the proximity detector 202 can be provided toa comparator or processor 804 which can, e.g., compare the output of theproximity detector to a threshold, to determine whether the object iswithin a range where the subsystem 806 should be enabled (or disabled,depending on what is desired). Multiple thresholds (e.g., stored digitalvalues) can be used, and more than one possible response can occur basedon the detected proximity of an object. For example, a first responsecan occur if an object is within a first proximity range, and a secondresponse can occur if the object is within a second proximity range.Exemplary responses can include starting various system and/or subsystemoperations. In FIG. 8, the block 802 represents a driver thatselectively drives the light source 204 to emit light. As mentionedabove, such a driver can be included as part of the optical proximitysensor 202, or can be external to the optical proximity sensor.

In the above described FIGS., an opaque barrier 208 was shown asseparating the light source 204 and the light detector 206. Inalternative embodiments, the opaque barrier 208 can be eliminated. Wherethe opaque barrier 208 is eliminated, it is likely that more PDs will beidentified as being crosstalk dominated, than if the opaque barrier 208were included. Nevertheless, using techniques described herein, anoptical proximity sensor without an opaque barrier separating the lightsource and the light detector can be configured to have a satisfactorySNR.

Optical proximity sensors, methods for use therewith, and systemsincluding optical proximity sensor are described above. Such opticalproximity sensors include a light source and a light detector, whereinthe light detector includes a plurality of individually selectablephotodiodes (PDs). During a calibration mode, individual PDs of theplurality of PDs of the light detector are tested to identify which PDs,if any, are crosstalk dominated. During an operation mode, the PDs ofthe light detector that were not identified as being crosstalk dominatedare used to produce a light detection value or signal that is useful fordetecting the presence, proximity and/or motion of an object within thesense region of the optical proximity sensor. By not using the PDs thatwere identified as being crosstalk dominated, the signal-to-noise ratioof the light detection value or signal is improved compared to if thecrosstalk dominated PDs were also used.

While various embodiments of the present invention have been describedabove, it should be understood that they have been presented by way ofexample, and not limitation. It will be apparent to persons skilled inthe relevant art that various changes in form and detail can be madetherein without departing from the spirit and scope of the invention.

The breadth and scope of the present invention should not be limited byany of the above-described exemplary embodiments, but should be definedonly in accordance with the following claims and their equivalents.

What is claimed is:
 1. A method for use with an optical proximitysensor, including a light source and a light detector, wherein the lightdetector includes a plurality of photodiodes (PDs), the methodcomprising: during a calibration mode of the optical proximity sensor,identifying certain PDs of the plurality of PDs of the light detectorare optical crosstalk dominated; and during an operation mode of theoptical proximity sensor that is separate from the calibration mode,using other of the PDs of the light detector that were not identified asbeing optical crosstalk dominated, and not using the certain PDs of thelight detector that were identified as being optical crosstalkdominated, to produce a light detection signal.
 2. The method of claim1, wherein the light detection signal is useful for detecting thepresence, proximity and/or motion of an object within the sense regionof the optical proximity sensor.
 3. The method of claim 1, wherein thecalibration mode includes: driving the light source to emit light whilethere is no object within a sense region of the optical proximity sensorand/or the light detector is covered by an opaque material; selectingeach of the PDs one at a time, while the light source is emitting light,to thereby determine and store a value for each of the PDs that isindicative of the amount of light detected by the PD; and identifying,based on the stored values, which individual PDs of the plurality of PDsof the light detector are optical crosstalk dominated.
 4. The method ofclaim 3, wherein identifying certain PDs of the plurality of PDs of thelight detector are optical crosstalk dominated comprises: comparing thestored values to a threshold value; and identifying, as being opticalcrosstalk dominated, each of the PDs whose stored value exceeds thethreshold.
 5. The method of claim 4, wherein the threshold is apredetermined fixed value or a programmable value.
 6. The method ofclaim 4, further comprising: determining a value that corresponds to adark current produced by a PD of the light detector; and determining thethreshold value based on the value that corresponds to the dark current.7. The method of claim 1, wherein the operational mode includesdeactivating or ignoring the certain PDs that were identified, duringthe calibration mode, as being optical crosstalk dominated.
 8. Themethod of claim 1, wherein the operational mode includes: driving thelight source to emit light; selecting each of the other PDs of the lightdetector one at a time, while the light source is emitting light, tothereby determine and store a value for each of the other PDs of thelight detector that is indicative of the amount of light detected by thePD; and adding the values stored for each of the other PDs that were notidentified as being optical crosstalk dominated to thereby produce alight detection value that is useful for detecting the presence,proximity and/or motion of an object within the sense region of opticalproximity sensor.
 9. The method of claim 1, wherein the operational modeincludes: driving the light source to emit light; selecting each of theother PDs that were not identified as being optical crosstalk dominatedone at a time, while the light source is emitting light, to therebydetermine and store a value for each of the other PDs that were notidentified as being optical crosstalk dominated, wherein the value isindicative of the amount of light detected by the PD; and adding thevalues stored for each of the other PDs that were not identified asbeing optical crosstalk dominated to thereby produce a light detectionvalue that is useful for detecting the presence, proximity and/or motionof an object within the sense region of optical proximity sensor. 10.The method of claim 1, wherein the operational mode includes: connectingtogether each of the other PDs that were not identified as being opticalcrosstalk dominated; driving the light source to emit light; and whilethe light source is emitting light, using the connected other PDs thatwere not identified as being optical crosstalk dominated to produce alight detection signal that is useful for detecting the presence,proximity and/or motion of an object within the sense region of opticalproximity sensor, wherein the light detection signal is indicative ofthe amount of light detected by connected together other PDs.
 11. Themethod of claim 1, further comprising: during the operational mode,using the light detection signal to detect the presence, proximityand/or motion of an object within the sense region of the opticalproximity sensor; and during the operational mode, selecting a responseor action in dependence on the presence, proximity and/or motion of theobject within the sense region of the optical proximity sensor.
 12. Anoptical proximity sensor, comprising: a light source that is selectivelydriven to emit light; a light detector including a plurality ofphotodiodes (PDs); and a controller configured to identify, during acalibration mode, certain PDs of the plurality of PDs of the lightdetector are optical crosstalk dominated, and cause, during anoperational mode, a light detection signal to be produced using theother of the PDs of the light detector that were not identified as beingoptical crosstalk dominated, and not using the certain PDs of the lightdetector that were identified as being optical crosstalk dominated 13.The optical proximity sensor of claim 12, further comprising an opaquebarrier between the light source and the light detector.
 14. The opticalproximity sensor of claim 12, further comprising: a driver thatselectively drives the light source to emit light; and memory orregisters; wherein the controller is configured to, during thecalibration mode cause the light source to be driven by the driver toemit light, cause each of the PDs to be selected one at a time while thelight source is emitting light, to thereby determine and store in thememory or registers a value for each of the PDs that is indicative ofthe amount of light detected by the PD; and identify, based on thestored values, the certain PDs of the plurality of PDs of the lightdetector are optical crosstalk dominated.
 15. The optical proximitysensor of claim 14, wherein the controller is configured to, during thecalibration mode, compare the stored values to a threshold value, andidentify as being optical crosstalk dominated each of the PDs whosestored value exceeds the threshold.
 16. The optical proximity sensor ofclaim 12, wherein the controller is configured to, during theoperational mode, cause the light source to be driven to emit light;cause each of the other PDs of the light detector to be individuallyselected one at a time, while the light source is emitting light, tothereby determine and store a value for each of the other PDs of thelight detector that is indicative of the amount of light detected by thePD; and add the values stored for each of the other PDs that were notidentified as being optical crosstalk dominated to thereby produce alight detection value that is useful for detecting the presence,proximity and/or motion of an object within the sense region of opticalproximity sensor.
 17. The optical proximity sensor of claim 12, whereinthe controller is configured to, during the operational mode, cause thelight source to be driven to emit light; cause each of the other PDs ofthe light detector that were not identified as being optical crosstalkdominated to be individually selected one at a time, while the lightsource is emitting light, to thereby determine and store a value foreach of the other PDs of the light detector that were not identified asbeing optical crosstalk dominated, wherein the value is indicative ofthe amount of light detected by the PD; and add the values stored foreach of the other PDs that were not identified as being opticalcrosstalk dominated to thereby produce a light detection value that isuseful for detecting the presence, proximity and/or motion of an objectwithin the sense region of optical proximity sensor.
 18. The opticalproximity sensor of claim 12, wherein the controller is configured to,during the operational mode, cause the light source to be driven to emitlight; cause each of the other PDs that were not identified as beingoptical crosstalk dominated to be connected together so that theconnected together other PDs that were not identified as being opticalcrosstalk dominated can be used to produce a light detection signal thatis useful for detecting the presence, proximity and/or motion of anobject within the sense region of optical proximity sensor, wherein thelight detection signal is indicative of the amount of light detected byconnected together other PDs.
 19. A system, comprising: a light sourcethat is selectively driven to emit light; a driver to selectively drivethe light source; a light detector including a plurality of photodiodes(PDs); and a controller configured to identify, during a calibrationmode, certain PDs of the plurality of PDs of the light detector areoptical crosstalk dominated, and cause, during an operational mode, alight detection value or signal to be produced using other of the PDs ofthe light detector that were not identified as being optical crosstalkdominated, and not using the certain PDs of the light detector that wereidentified as being optical crosstalk dominated.
 20. The system of claim19, further comprising: a subsystem capable of being enabled anddisabled; and a comparator or processor that receives the lightdetection value or signal and selectively enables or disables thesubsystem in dependence thereon, wherein the subsystem is at least oneof: a touch-screen, a display, a backlight, a virtual scroll wheel, avirtual keypad, a navigation pad, a camera, a sensor, a centralprocessing unit (CPU), or a mechanical actuator.